'Out of sight' groundwater vital to meet growing demand

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Dr Mike Jones

Dr Mike Jones has managed to find enough groundwater to keep the taps flowing for an extra one million customers since joining Thames Water in 1999.

That is pure gold to a hydrogeologist operating in the “seriously water-stressed” South East region of the country, especially when London alone is expected to rise in population by 1.8 million people by 2040.

Demand is clearly rising, while conventional natural water sources are exhausted. Over the next 10 years Thames Water aims to provide much of the additional water its customers will need through managing demand. This will be by reducing leakage, putting in meters and giving customers practical help and advice on saving water. Beyond that is a complex job for Mike and the rest of the water resources experts.

With nearly 2,000 Twitter followers, Mike (@GroundwaterMike) is determined to improve people’s awareness and understanding of groundwater, “which is often out of sight and out of mind”. 

He said: “To deliver the 30% of our water supply that comes from groundwater, we have 175 sources comprising 350 boreholes and wells, the oldest being constructed 170 years ago. 

“So, to secure this groundwater supply, not only does it require monitoring the condition of the boreholes and wells, but also how much we can pump during drought when groundwater levels are low.” 

Working with its regulators, his team aims to maximise the amount of groundwater it can pump sustainably without damaging the environment. Now, however, they’re trying to make even better use of groundwater by increasing the amount of water stored underground. 

This will build on existing operations that stores up to 10% of London’s water supply in the chalk and sand aquifers 20 to 70 metres beneath north London, which are kept topped up with potable water ready for use during drought.

He said: “It’s not well understood that around 95% of the world’s available freshwater is right beneath your feet, and that this is groundwater, present naturally underground in permeable rocks and sediments called aquifers. 

“We don’t often see groundwater, but during drought, groundwater acts like a savings account, with aquifers storing water for those non-rainy days. It’s rewarding when people grasp its crucial role in supporting river flows and water supply, including London’s managed aquifer recharge scheme.”  

He said the best part of his job is “exploring and developing new conventional and innovative groundwater sources”, and then delivering them into supply. 

“Since I’ve been at Thames Water I’ve delivered or directed all the hydrogeological inputs in the development of our groundwater abstraction capability, increasing that capability by around 180 Ml/d (million litres per day) across London and the Thames Valley,” he added. “That’s enough to provide a water supply to an extra one million customers.”

With it being so important to Thames Water and its customers, it’s important to realise that groundwater can be vulnerable to contamination from activities using fuel, pesticides and solvents, such as industrial operations, infrastructure development and agriculture.

Mike said: “As we become more aware of the environment around us and the need to protect it, we shouldn’t forget our hidden asset, groundwater, and the need to protect it too.”

Together with a team of hydrogeologists, water resource and treatment asset modellers, Mike works to understand the sustainable performance of the company’s abstraction, storage and treatment assets, “particularly during drought”, as well as their response to water quality and future climate challenges.

This means plenty of variety. “It can include assessing the impact of contaminants and urban development on groundwater, meeting local stakeholders to explain how our groundwater abstractions interact with the environment, as well as supporting the development of new tools to prioritise water treatment investment,” he said.